5.(1) C2H6O C2H5OH 羟基 羧基(2) NaO-C6H4-COONa + CO2 + H2O ==> HO-C6H4-COONa + NaHCO3(3)对羟基-苯甲酸 水解(4) HO-C6H4-COOC2H5(5)?